Modular roller-top conveyor belt

ABSTRACT

A modular roller-top conveyor belt constructed of a series of rows of belt modules having hinge elements at opposite ends of each row. The hinge elements of each row are interleaved with the hinge elements of an adjacent row and interlinked by hinge pins to form an endless conveyor belt. Each of the belt modules includes a body section extending between opposite ends of each row in the direction of belt travel. Cavities formed in at least some of the modules open onto an upper conveying surface of the belt. Rollers residing in the cavities protrude onto the upper conveying surface to engage conveyed articles in rolling, low-friction contact. The rollers may be cylindrical rollers that rotate about axles, spherical balls that rotate in all directions, or caster-like roller assemblies.

This application is continuation of Ser. No. 09/629,776 filed Jul. 31,2000 now U.S. Pat. No. 6,209,714 which is a continuation of Ser. No.09/184,926 filed Nov. 2, 1998 now U.S. Pat. No. 6,148,990.

BACKGROUND

The invention relates to power-driven conveyors and, more particularly,to modular conveyor belts constructed of rows of belt modules hingedlyinterlinked end-to-end by hinge pins.

Conventional modular conveyor belts and chains are made up of modularlinks, or belt modules, arranged in rows. Spaced apart link endsextending from each end of the modules include aligned apertures. Thelink ends along one end of a row of modules are interleaved with thelink ends of an adjacent row. A pivot rod, or hinge pin, journalled inthe aligned apertures of the end-to-end-connected rows, connectsadjacent rows together to form an endless conveyor belt capable ofarticulating about a drive sprocket.

In many industrial applications, articles are allowed to accumulate on acontinuously moving conveyor belt before being off-loaded. Frictionbetween the conveying surface of the moving belt and the accumulatedarticles causes the articles to push against each other increasingbackline pressure. Backline pressure can cause damage to the articles,excessively load the conveyor belt and its drive components, andaccelerate belt wear. Rotatable elements, such as rollers, in rollingcontact with the undersides of conveyed articles have been used toreduce friction and lower backline pressure.

In other conveyor applications, articles must be pushed off the side ofa constantly moving or stop-and-go conveyor belt. Rollers oriented withtheir axes of rotation in the direction of belt travel have been used toprovide low friction rolling contact with the undersides of conveyedarticles being pushed off the side of a conveyor.

Arscott U.S. Pat. No. 4,231,469, issued Nov. 4, 1980, discloses aconveyor comprising a plurality of interconnected cradles and arotatable member mounted in each cradle. The rotatable members extendabove the respective cradle for rolling contact with an object placed onthe conveyor to allow the objects to move relative to the conveyor. TheArscott patent discloses rotatable members with axes of rotation in thedirection of belt travel for side off-loading and perpendicular to thedirection of belt travel for low backline pressure.

One shortcoming of the Arscott conveyor and other roller-top belts isthat they are difficult to clean owing to the many surfaces and nooksand crannies associated with the rollers. Cleanability is especiallyimportant in some industries, such as meat-handling, where bacteria canform in and spread from difficult-to-clean areas.

Another shortcoming of many low backline pressure conveyors is theplacement of a roller on the pivot rod. Such a placement requires feweror thinner link ends resulting in less belt pull strength or narrowrollers resulting in high contact pressure on conveyed articles. Thus,there is a need for a modular conveyor belt that features low backlinepressure or low-friction side transfer and that is easy to clean.

SUMMARY

These needs and others are satisfied by the invention, which provides amodular roller-top conveyor belt. The belt is constructed of a series ofrows of belt modules having hinge elements at opposite ends of each row.The hinge elements of one row are interleaved with the hinge elements ofan adjacent row. Hinge pins interlink the interleaved hinge elements ofadjacent rows to form an endless conveyor belt with pivotable jointsbetween each row. Each row is constructed of one or more belt modules.Each module includes a body section extending between first and secondends in the direction of belt travel. The body section includes a bottomsurface and an opposite upper deck that forms an upper surface. At leastone cavity is formed in the body section of one or more of the modules.The cavity opens onto the upper surface. A roller residing in the cavityengages conveyed articles in rolling, low-friction contact.

In various versions of the belt of the invention, the rollers arecylinders for rotation about axes parallel to or perpendicular to thedirection of belt travel or balls for omnidirectional rotation.

In one version of the belt of the invention, the cavity extends from theupper surface completely through the body section to an opening in thebottom surface to allow debris to fall through. In another version, thebelt has a transverse drive element extending from the bottom surfaceand the cavity does not extend through the drive element to allow forplacement of drive sprockets across the entire width of the belt row.

In versions with a cylindrical roller, the belt includes an axle thatfits through a central bore in the roller. Opposite walls of the cavityhave collinear holes to support the ends of the axle. In a versionhaving more than one cavity in the body section, the collinear holes canbe extended to join the cavities and form a passageway along atransverse axis to admit a single axle on which all the rollers ride.The roller can be made of a rubber material with its bore lined by abushing to receive the axle. In a version designed for side transfer ofarticles, at least one of the collinear holes opens into a gap betweenconsecutive hinge elements for easy insertion of the axle during moduleconstruction. As the belt is put together, the axle is retained in theholes by an interleaved hinge element of an adjacent belt row disposedin the gap. To guide articles that drop onto the conveyor on an edge orotherwise skewed orientation, another version of the belt of theinvention features an upwardly sloping, for example, convex, uppersurface. The upper surface rises from the first and second ends of thebelt rows toward the roller. This construction tends to guide the skewedarticle into a conveying position atop the roller. A version with apivotable support mounted in the cavity and a roller and axle rotatablysupported in the support provides a caster-like action that gives therollers the versatility to roll in all directions.

In one version of the belt of the invention for use with roller balls,the cavity includes a recessed surface that supports bearing elements,which provide low-friction bearing surfaces for the ball. The bearingselements are ridges rising from the recessed surface of the cavity. Inanother version, the bearing elements include a plurality of ballbearings in a ball bearing holder. A cover has a circular aperture witha diameter less than the diameter of the ball to retain it in the cavitywith just a portion of the ball protruding above the surface of thecover into rolling contact with conveyed articles. The cover can beintegrally molded with the upper deck to engage retention structure onthe upper deck in snap-fit retention. In one integrally molded version,the cover includes a lip defining the circular aperture whose diameteris adjustable by deformation, for example, from a first diameter to asecond diameter. The first diameter is greater than the diameter of theball to allow the ball to be installed in the cavity. The seconddiameter is less than the diameter of the ball to retain the ball in thecavity with a portion of the ball protruding through the cover intorolling contact with conveyed articles. In another version, the coverhas sloping sides to guide askew articles into position atop the rollerballs.

DRAWINGS

These and other advantages, features, and aspects of the invention aredescribed in more detail in the following description, appended claims,and accompanying drawings in which:

FIG. 1 is top plan view of a portion of one version of a conveyor belthaving features of the invention;

FIG. 2A is a top perspective view of a belt module usable with theconveyor belt of FIG. 1;

FIG. 2B is a bottom perspective view of the belt module of FIG. 2A;

FIG. 3 is a perspective view of one version of roller and axle havingfeatures of the invention;

FIG. 4 is a top perspective view of another belt module for use with aconveyor belt having features of the invention;

FIG. 5 is a bottom plan view of a portion of a conveyor belt constructedof modules as in FIG. 4;

FIG. 6 is a sectional elevation view of the belt module of FIG. 4 viewedalong cut line 6 of FIG. 4;

FIG. 7 is a top perspective view of yet another belt module for use witha conveyor belt having features of the invention, including a rollerball;

FIG. 8 is a top plan view of the belt module of FIG. 7;

FIG. 9A is a fragmentary cross section view of the belt module of FIG. 8along cut line 9—9, showing a roller ball and cover in an undeformedstate for insertion of the ball;

FIG. 9B is a fragmentary cross section as in FIG. 9A showing the coverdeformed to retain the ball;

FIG. 10 is a top perspective view of another belt module having featuresof the invention, including a roller ball retaining cover;

FIG. 11 is an exploded perspective view of the belt module, cover, androller balls of FIG. 10;

FIG. 12 is a blow-up of one of the roller ball cavities of FIG. 11;

FIG. 13 is a top perspective view of another belt module having featuresof the invention, including a cover for transfer ball assemblies;

FIG. 14 is an exploded perspective view of the belt module of FIG. 13,showing the cover, belt module, and transfer ball assemblies;

FIG. 15 is an exploded elevation view of the belt module of FIG. 13;

FIG. 16 is a top plan view of another belt module having features of theinvention, including caster roller assemblies; and

FIG. 17 is a partial cross section view of the belt module of FIG. 16along cut line 17—17.

DESCRIPTION

A portion of an exemplary version of a modular roller-top conveyor belthaving features of the invention is shown in FIG. 1. The belt depictedhas many of the features of and is similar to the Intralox Series 800modular plastic conveyor belt manufactured by Intralox, Inc. of Harahan,La., a subsidiary of the assignee of this invention. The belt 20 isconstructed of a series of rows 22A-22C of belt modules 24, 25, eachshown with one or more rollers 48. In this version, each row 22 includesa short edge module 25 at one edge and a long edge module 24 at theopposite edge. Other constructions are possible. For example, each rowcould be made up of a single module extending across the entire width ofthe belt. Alternatively, the belt could include one or more internalmodules positioned between the edge modules 24, 25. As anotheralternative, modules without rollers could be interspersed with moduleswith rollers in a variety of roller patterns, such as no rollers onevery other row or alternating rollers across the width of the belt fromrow to row. Although the version shown in FIG. 1 and all otherconstructions having multiple modules in each row are preferablyarranged in a bricklaid pattern, it would be possible to construct abelt having features of the invention in an arrangement with acontinuous seam along the length of the belt between adjacentside-by-side and end-to-end modules. In all of these belt constructions,wider belts can be made by building each row with more or wider modules.

As shown in FIG. 1 and shown in more detail in FIGS. 2A and 2B, each row22 extends longitudinally in the direction of belt travel 23 from afirst end 26 to a second end 28. A first plurality of hinge elements 30and a second plurality of hinge elements 32 extend from an intermediatemodule body section 34 at the first and second ends. Axially alignedholes 36 are formed in the hinge elements at each end of the row.Consecutive rows, 22A and 22B, for instance, are interlinked hinge-likeby a hinge pin 38 extending through a lateral passage formed by thealigned holes of interleaved hinge elements 30, 32 disposed at adjacentends of consecutive rows. All the rows of the belt are connected in thisway to form an endless conveyor belt capable of articulating about driveand idler sprockets (not shown). The hinge between consecutive rows canbe realized equivalently in other ways. For example, stubs protrudinglaterally from the sides of the hinge elements at the first end of therow and extending into aligned holes in the interleaved set of hingeelements of an adjacent row could be used to hingedly interconnectadjacent rows into a belt.

The body section 34 includes a bottom surface 40 and an opposite upperdeck 42 that forms a substantially continuous upper surface 44, exceptfor cavities 46 opening onto the upper surface. A roller 48 is rotatablydisposed in each cavity. A salient portion of the roller protrudes abovethe upper surface to engage conveyed articles in low-friction rollingcontact. In the version shown in FIG. 2A-2B, the rollers are cylindricalin shape with a central bore 50 along the major axis 52 of the cylinder.The major axis in this example is perpendicular to the direction of belttravel 23. Collinear holes 54, 55 in opposite walls 56, 57 of the cavity46 support opposite ends of an axle 58 that extends through the bore ofthe roller. With multiple cavities across the width of a module, thecollinear holes associated with each cavity can be arranged tocommunicate with each other and the cavities to form a transversepassageway along an axis of rotation perpendicular to belt travel. Asingle axle extending through the passageway supports all the rollers onthe module, although individual axles could be used. An opening 60 in atleast one side edge of the modules allows the axle to be inserted intothe passageway and through the rollers. If the opening is in only oneside of the modules, the passageway terminates in a blind end thatblocks the axle from working its way out.

A drive element 62 extends across the width of the module. The driveelement has drive surfaces 63, 64 on each side for driving engagement bya drive sprocket, for example. In a preferred version, the roller cavityformed in the body section does not extend through the drive element. Inthis way, drive sprockets can be positioned anywhere along the width ofthe belt. If an uninterrupted drive element is not necessary, the cavitycould extend through the drive element. The upper surface 44 of the beltslopes, or curves, upwardly from the first end 26 and the second end 28of each row toward the middle of each row. The slope could be planar,but is preferably convex, to help guide articles, such as boxes thatland on the belt comer-first, onto the rollers. The upwardly slopingupper surface also allows the roller cavity to be positioned higher toavoid interruption of the drive element. In the version shown, the uppersurface 44 is substantially continuous, except for the roller positions,for cleanability. The roller and cavity can be cleaned from the bottomside through the access voids 65, 66 flanking the drive element. Thevoids also allow grime and debris to fall from the roller cavity. Thus,the rollers of the belt shown in FIGS. 1-2, with an axis of rollerrotation perpendicular to the direction of belt travel, provide lowbackline pressure to conveyed articles that accumulate on the belt.

Details of a preferred version of the roller 48 and axle 58 used in theembodiment of the belt of FIGS. 1-2 are shown in FIG. 3. The roller is acircular cylinder having a bore 50 along its major axis 52. The edges67, 68 of the roller are preferably rounded to provide smooth surfacesless likely to catch on edges of conveyed articles. For durability andwear resistance, the roller is preferably made of acetal, nylon, steelwith bronze bearings, or polypropylene. It can be molded or machined.The roller axle 58 is preferably made of stainless spring steel, carbonspring steel, common stainless steel, or nylon. The metal axles wouldtypically be cold drawn for a good finish. The belt module is preferablymade of acetal, polyethylene, nylon, or polypropylene. The bore could belined by a bushing pressed or molded into the bore. The bushing could bemade of brass, bronze, or another durable material. With a durablebushing providing a bearing surface for the axle, the roller could bemade of a less expensive material or less durable material, such is asrubber.

The rollers of FIG. 3 could likewise be used in another version of theroller-top belt of the invention as shown in FIGS. 4-6. In this version,the belt module 70 depicted is similar to and has many of the featuresof the Intralox Series 400 modular plastic conveyor belt modules. Thepurpose of the belt constructed of the modules is to allow conveyedarticles to be transferred off the side of the belt in the direction ofthe arrow 72. In this version of the belt, the axis of rotation 73 ofthe rollers 48 is in the direction of belt travel 71. A cavity 76 formedin the body section 78 extends through the thickness of the module toallow debris to drop through easily. Collinear holes 80, 81 in oppositewalls 82, 83 of the cavity support the ends of an axle 84 journalled inthe bore 50 through the roller. The cavity and the holes can be moldedor machined into the belt module. At least one of the holes opens into agap 74 between consecutive hinge elements 85A, 85B of a module. Once inplace, the axle is prevented from working its way out of the hole by theinterleaved hinge element 86 of an adjacent row extending into the gap.With the axis of rotation parallel to belt travel, articles can beeasily transferred off the side of a belt constructed of the modules ofFIGS. 4-6 by a lateral push. Although shown with a closed, flat topsurface, the belt could alternatively include open areas for drainage orreduced mass.

Other versions of rollers and belt modules having further features ofthe invention are illustrated in FIGS. 7-15. The integral module 88 ofFIGS. 7-8 is shown by way of example as having many of thecharacteristics of the Intralox Series 800 module including a bodysection 89 and an upper deck 90. A recessed surface 93 formed in thebody section and opening onto the upper deck bounds a partial sphericalcavity 92 sized to contain a roller ball 94. Raised ribs 96 extendupwardly from the recessed spherical surface in the manner of lines oflongitude from a polar center support 95 to provide sliding bearingsupport for the ball 96. As seen in FIG. 12, small openings 98 betweenthe ribs in the bottom of the recessed surface allow the cavity to becleaned by a water spray and to drain. A cover 99 extending from theupper deck 90 serves to extend the cavity upwardly and to provide asloping surface to direct askew articles into orderly contact with theball. The ribs and center support allow the ball to rotate freely in alldirections.

The ball is retained in the cavity by features shown in FIGS. 9A and 9B.In FIG. 9A, the cover 99A is shown in its original shape with a lip 100Aat the upper end of the recessed surface bordering a circular aperture104A having a first diameter greater than the diameter of the ball 94for easy insertion of the ball into the cavity. After the ball isinserted in the cavity, an upper adjustable portion 101 of the cover 99Bis deformed by pressure applied with a component of force roughly in thedirection of arrow 102 (FIG. 9B) to bend the lip 100B to decrease thediameter of the circular aperture 104B to a second diameter less thanthe diameter of the ball to retain it free to rotate in the cavity witha salient portion protruding through the aperture into rolling contactwith conveyed articles. Deformation pressure can be applied, forexample, by a hollow cylindrical tool that is pressed down vertically onthe cover to adjust its shape from that in FIG. 9A to that in FIG. 9B.The entire belt module, including cover, is preferably integrally moldedof a plastic material, but could be machined or cast of metal. The covercould be a separate piece held in place by gluing or spin-welding. Theball could be molded or formed in other ways of the same or othermaterials, including metals.

Another version of roller ball retention is shown in FIGS. 11-12. Inthis version, the cover 106 shown is oblong with three circularapertures 107 formed therein. The diameter of each aperture is less thanthe diameter of the roller balls 94. The cover has sloping sides 108 toguide askew articles into orderly contact with the roller balls. Thecover also has retention elements in the form of tabs 110 that mate withretention structure in the form of rectangular slots 112 formed in theupper deck 90 of the module 105. The tabs snap into the slots and retainthe entrapped balls free to rotate in the cavities, The covers can beremoved to replace worn balls.

Yet another version of a belt module having a roller top is illustratedin FIGS. 13-15. In this version, conventional metal transfer ballassemblies 114, such as those available through the McMaster-Carrcatalog, are used. The assemblies include a metal ball 116 supported ina holder 118 on a plurality of ball bearings (not shown). A belt module120, similar to that in FIG. 11, provides cavities 122 for the transferball assemblies. The cavities are generally open, at least down to thedrive bar 124, to admit the self-contained assemblies. A shoulder 126formed on the upper deck 128 of the module supports the transfer ballassembly, which has a circumferential flange 130 that rests on theshoulder. A cover 132 has retention tabs 110 that mate with retentionstructure in the form of rectangular slots 112 formed in the upper deck.The cover for the transfer ball assemblies includes indentations 133conforming to the shape of the upper portion of the transfer ballassemblies for a snug fit. In other respects, the cover is similar tothat of FIGS. 11-12 and retains the transfer ball assemblies in the beltmovable with only a salient portion of the ball protruding in freelyrolling contact with conveyed articles.

Another way of achieving multidirectional rolling contact with conveyedarticles is shown in FIGS. 16 and 17. Instead of a transfer ball, thebelt module includes a caster assembly 136 disposed in a generallycylindrical cavity 134. The caster assembly comprises a roller 138 andaxle 140 mounted in a rotatable support 142. The roller rotates aboutthe axis of the axle. A pivot 144 at the bottom of the support allowsthe entire caster assembly to rotate about a vertical axis 146 asindicated by two-headed arrow 148. The axle is supported at its ends bythe sides of the support, which include holes into which the axleextends. Although the roller axle could, it preferably does notintersect the vertical pivot axis to provide more freely swinging casteraction to the roller in contact with conveyed articles. Preferably, thepivot axis and the axis of the axle lie in mutually perpendicularplanes.

Thus, the invention has been described with respect to various versionsof rollers, both cylindrical rollers with axles and spherical balls onbearing elements. Even so, those skilled in the art will easilyappreciate that other modifications of the exemplary versions arepossible without materially departing from the novel teachings andadvantages of the invention. For example, the axles need not bejournalled in a bore through the cylindrical rollers, but could insteadbe fixedly attached to the rollers and rotate in the supporting holes ineach wall. The axles need not extend through the rollers, but could berealized as stubs extending from each flat end of the roller into thesupport holes. As the examples suggest, these and other modificationsare intended to be included within the scope of the invention as definedin the following claims.

What is claimed is:
 1. A modular conveyor belt comprising a series ofrows of belt modules and hinge pins hingedly interlinking consecutivebelt rows end-to-end to form a conveyor belt, each row including atleast one module comprising a body section extending from a first end toa second end in the direction of belt travel, a first plurality of hingeelements along the first end, and a second plurality of hinge elementsalong the second end, the first plurality of hinge elements of a rowbeing interleaved with the second plurality of hinge elements of anadjacent row and pivotally joined by a hinge pin in a hinged connectionbetween consecutive rows of belt modules, wherein the body section of atleast some of the modules includes an upper surface, a plurality ofcavities disposed across the width of the row and opening onto the uppersurface, and a roller rotatably disposed in each of the cavities with asalient portion of each roller protruding above the upper surface toengage conveyed articles in rolling contact.
 2. A modular conveyor beltas in claim 1 wherein each roller is cylindrically-shaped and rotatesabout an axis of rotation perpendicular to the direction of belt travel.3. A modular conveyor belt as in claim 1 wherein each roller iscylindrically-shaped and rotates about an axis of rotation parallel tothe direction of belt travel.
 4. A modular conveyor belt as in claim 1wherein each roller comprises a roller ball.
 5. A modular conveyor beltas in claim 1 wherein each roller is cylindrically-shaped and rotatesabout an axis of rotation and is further pivotable about a vertical axisperpendicular to the axis of rotation.
 6. A modular conveyor belt as inclaim 1 further comprising a cover over the roller and wherein the coverforms an aperture therethrough through which the salient portion of theroller protrudes.
 7. A modular conveyor belt as in claim 6 wherein thecover includes retention elements and the body section includesretention structure that engages the retention elements to retain thecover in place.
 8. A modular conveyor belt as in claim 7 wherein theretention elements include tabs that mate with the retention structurein a snap fit.
 9. A modular conveyor belt as in claim 6 wherein thecover includes a plurality of apertures.
 10. A modular conveyor belt asin claim 6 wherein the cover further includes sloping sides.
 11. Amodular conveyor belt as in claim 1 wherein the plurality of cavities isarranged in line across the width of a row.
 12. A modular conveyor beltcomprising a series of rows of belt modules and hinge pins hingedlyinterlinking consecutive belt rows end-to-end to form a conveyor belt,each row including at least one module comprising a body sectionextending from a first end to a second end in the direction of belttravel, a first plurality of hinge elements along the first end, and asecond plurality of hinge elements along the second end, the firstplurality of hinge elements of a row being interleaved with the secondplurality of hinge elements of an adjacent row and pivotally joined by ahinge pin in a hinged connection between consecutive rows of beltmodules, wherein the body section of at least some of the modulesincludes an upper surface, a plurality of cavities disposed across thewidth of the row and opening onto the upper surface, and a rollerassembly disposed in the cavities, wherein the roller assembly includesa support and a roller rotatably mounted thereto with a salient portionof each roller protruding from the support to engage conveyed articlesin rolling contact.
 13. A modular conveyor belt as in claim 12 whereinthe roller assembly further includes an axle supported by the supportand about which the roller rotates.
 14. A modular conveyor belt as inclaim 13 wherein the axis of the axle is perpendicular to the directionof belt travel.
 15. A modular conveyor belt as in claim 13 wherein theaxis of the axle is in the direction of belt travel.
 16. A modularconveyor belt comprising a series of rows of belt modules and hinge pinshingedly interlinking consecutive belt rows end-to-end to form aconveyor belt, each row including at least one module comprising a bodysection extending from a first end to a second end in the direction ofbelt travel, a first plurality of hinge elements along the first end,and a second plurality of hinge elements along the second end, the firstplurality of hinge elements of a row being interleaved with the secondplurality of hinge elements of an adjacent row and pivotally joined by ahinge pin in a hinged connection between consecutive rows of beltmodules, wherein at least some of the modules include a sloping uppersurface, at least one cavity opening onto the sloping upper surface, anda roller rotatably disposed in the cavity with a salient portion of theroller protruding from the cavity to engage conveyed articles in rollingcontact.
 17. A modular conveyor belt as in claim 16 wherein the slopingupper surface curves upwardly from the first end and the second endtoward the middle of each row.
 18. A modular conveyor belt as in claim16 wherein the roller rotates about an axis of rotation perpendicular tobelt travel.
 19. A modular conveyor belt as in claim 16 wherein thesloping upper surface forms part of the body section.
 20. A modularconveyor belt as in claim 16 wherein the sloping upper surface extendsacross the width of the row.